All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Shlomo Pongratz <shlomop@mellanox.com>
Cc: axboe@kernel.dk, linux-scsi@vger.kernel.org
Subject: Re: [PATCH] block/null_blk: Fix completion processing from LIFO to FIFO
Date: Thu, 6 Feb 2014 08:35:42 -0800	[thread overview]
Message-ID: <20140206163542.GA30008@infradead.org> (raw)
In-Reply-To: <1391704397-26816-1-git-send-email-shlomop@mellanox.com>

On Thu, Feb 06, 2014 at 06:33:17PM +0200, Shlomo Pongratz wrote:
> The completion queue is implemented using lockless list.
> 
> The llist_add is adds the events to the list head which is a push operation.
> The processing of the completion elements is done by disconnecting all the
> pushed elements and iterating over the disconnected list. The problem is
> that the processing is done in reverse order w.r.t order of the insertion
> i.e. LIFO processing. By reversing the disconnected list which is done in
> linear time the desired FIFO processing is achieved.

I think it should just switch to using __smp_call_function_single
directly, mirroring commit 3d6efbf62c797a2924785f482e4ce8aa8820ec72 for
the blk-mq core.

I've actually a patch in the queue that allows generic request
completion offloading similar to blk_complete_request() in the old
request code, but it'll need a bit more polishing first.


  reply	other threads:[~2014-02-06 16:35 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-06 16:33 [PATCH] block/null_blk: Fix completion processing from LIFO to FIFO Shlomo Pongratz
2014-02-06 16:35 ` Christoph Hellwig [this message]
2014-02-06 19:23   ` Jens Axboe

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20140206163542.GA30008@infradead.org \
    --to=hch@infradead.org \
    --cc=axboe@kernel.dk \
    --cc=linux-scsi@vger.kernel.org \
    --cc=shlomop@mellanox.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.